I have a 2006 Forester. Recently I noticed that I was having a problem with the alarm key fob. The battery seemed like it was dying and would open but often not lock the car. I took out the battery and checked it and tester said it was okay. Changed the battery with a new one and it unlocks slightly better but still will not lock car. Used spare fob that came with the car and no problem. Do these fobs just spontaneously break. I did not drop it or damage it recently that I know of. Any suggestions? What do these fobs cost new and do they need to be programmed, and ... do I need a new one???